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/* See LICENSE file for copyright and license details. */
#include "internals.h"
#define ta libzahl_tmp_divmod_a
#define tb libzahl_tmp_divmod_b
#define td libzahl_tmp_divmod_d
#define tds_proper libzahl_tmp_divmod_ds
static inline void
zdivmod_impl(z_t a, z_t b, z_t c, z_t d)
{
size_t c_bits, d_bits, bit, i;
static z_t tds[BITS_PER_CHAR];
c_bits = zbits(c);
d_bits = zbits(d);
bit = c_bits - d_bits;
zlsh(td, d, bit);
SET_SIGNUM(td, 1);
if (zcmpmag(td, c) > 0) {
zrsh(td, td, 1);
bit -= 1;
}
SET_SIGNUM(ta, 0);
zabs(tb, c);
if (unlikely(bit <= BITS_PER_CHAR)) {
for (;;) {
if (zcmpmag(td, tb) <= 0) {
zsub_unsigned(tb, tb, td);
zbset(ta, ta, bit, 1);
}
if (!bit-- || zzero(tb))
goto done;
zrsh(td, td, 1);
}
} else {
for (i = 0; i < BITS_PER_CHAR; i++) {
zrsh(tds_proper[i], td, i);
tds[i]->used = tds_proper[i]->used;
tds[i]->sign = tds_proper[i]->sign;
tds[i]->chars = tds_proper[i]->chars;
}
for (;;) {
for (i = 0; i < BITS_PER_CHAR; i++) {
if (zcmpmag(tds[i], tb) <= 0) {
zsub_unsigned(tb, tb, tds[i]);
zbset(ta, ta, bit, 1);
}
if (!bit-- || zzero(tb))
goto done;
}
for (i = MIN(bit, BITS_PER_CHAR - 1) + 1; i--;)
zrsh_taint(tds[i], BITS_PER_CHAR);
}
}
done:
zswap(a, ta);
zswap(b, tb);
}
void
zdivmod(z_t a, z_t b, z_t c, z_t d)
{
int sign, cmpmag;
sign = zsignum(c) * zsignum(d);
if (unlikely(!sign)) {
if (unlikely(!zzero(c))) {
libzahl_failure(-ZERROR_DIV_0);
} else if (unlikely(zzero(d))) {
libzahl_failure(-ZERROR_0_DIV_0);
} else {
SET_SIGNUM(a, 0);
SET_SIGNUM(b, 0);
}
return;
} else if (cmpmag = zcmpmag(c, d), unlikely(cmpmag <= 0)) {
if (unlikely(cmpmag == 0)) {
zseti(a, sign);
SET_SIGNUM(b, 0);
} else {
SET(b, c);
SET_SIGNUM(b, 1);
SET_SIGNUM(a, 0);
}
return;
}
zdivmod_impl(a, b, c, d);
SET_SIGNUM(a, sign);
}
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